Splitting LC Flow to MS & Secondary Detector

[OK-Chemist]

I am needing to setup a "split flow" configuration post-column on an HPLC... The analytical column is running at 1.25mL/min, and I need to send ~ 1.0mL/min to a UV-VIS and ~ 0.25mL/min to the MS. I was directed to a splitter assembly on Sigma-Aldrich but it costs over $2,000. I was wondering if anyone can suggest a simpler device or assembly I can make myself which will do the trick. The splitter through Sigma-Aldrich looks really nice, with adjustable splits from 1:1 to 1:20; however, I more than likely do not require that degree of accuracy.

Thanks for any suggestions!

[U0mrj1K]

Hi there,

I wonder whether you might consider using a simple T-piece (as used for T-infusions) in order to achieve the desired effect? Obviously you'll not have the flexibility as the Sigma-option with regards to changing split ratios on-the-fly, but you can almost certainly set up a fixed split ratio by altering the length of tubing/internal diameters of the tubes going to either detector.

Fingers crossed someone on here can offer you a little more guidance on how this might be achieved.

U0mrj1K

[lmh]

Yes, a T-piece should work. One minor point, to keep dead-volume to a minimum, I'd be inclined to keep the tubing to the MS as thin as you can. You don't really want a vast long curly tube (and certainly not a very fat tube) on the inlet side of either detector, unless you particularly want broad peaks! You can fine-tune the split ratio by adding tubing to the exit side of the UV-Vis detector (the same applies to any other detector that isn't horrendously pressure-sensitive).

[lmh]

oooh... but another thought: do you really need to split? Unless you particularly need such a high flow through the UV/VIS for other reasons (for example, you're collecting fractions), why not buy a narrow-bore column and put the detectors in series?